Mine was doing the same thing but it was coming from right in front of the sunroof wear the overhead console map lights are. If I pushed up on the overhead console the rattling would stop but soon after I let go the rattling would start up again. My car was still under warranty so I took it to the dealer. They took my RS for a test drive to re-creat the issues that I was having and then ordered some replacements parts where overhead sunglass tray console was at. After I receive my car back from the dealer there was no more rattles coming from the headliner and it was free of charge, covered under my warranty.